Sunday, September 8th, 2013

The Story Behind Tire Pressure Monitoring System (TPMS)

TPMS, aside from the last three letters being the scourge of every male on the face of the earth, this is one of the most misunderstood and misaligned function on today’s vehicles.

Honestly speaking this function was designed and has succeeded to save thousands of lives, merely by keeping tires inflated to their proper amounts. TPMS stands for Tire Pressure Monitoring System. To most it’s that orange lamp on the dash that looks like a tire with an explanation point in the middle.

Flashback to the middle to late nineties, Ford and Firestone were in the middle of a finger pointing session about who was to blame for the 100 plus deaths due to Explorer roll overs. Of course Ford blamed Firestone for the tire construction as Firestone blamed Ford for not having a more defined center of gravity.

TPMS sensor and component

TPMS sensor and component

As a service technician, and as a father, after the first few roll overs I blame the drivers and owners for not either replacing those tires before the Ford transfer campaign, or not being hyper vigilant at monitoring tire pressures every day. Because of this the government felt that they had to take control of yet one more thing in our lives.

Whether that was a good thing or bad is not the point, the point is that every time we get behind the wheel of a vehicle we are in charge of a 3000 pound or heavier killing machine. And not only do we put ourselves in jeopardy but also the lives of so many innocent people that we have contact with.

What exactly is a tire pressure monitor? Basically it’s a battery powered sensor that can monitor the pressure and temperature of the environment inside the tire. These sensors take these measurements and then change them into a signal that can be transmitted to the tire pressure control module and then sent to the dash or instrument panel that either turns on a light or can actually broadcast the position temperature and pressure of said tire.

As complex as these sensors are, their cost is low as compared to most Bluetooth devises. Expect the average cost to be in the $130.00-160.00 area. Because these sensors are completely separate from each other yet work in unison there are certain failures that may be connected or singular in repairs. Obviously if there is a failure within the control module then the information is either faulty or non-existent. This is truly a “garbage in, garbage out” scenario. If one of the sensors fail for any reason with the exception of battery failure usually means a single sensor replacement.

Low Pressure Tire Light

Low Pressure Tire Light

The engineers with their uncanny sense of “lets hang nine things on a single component that is held on with 2 bolts attitude” completely reversed themselves and noting that the weak link is the battery, devised a system that allows the battery to turn off until the tires start to turn that allows them to “wake up”. Some vehicles have sensors in the spare tire and by rights and design they should never be monitored but out in the field we have found that theory to be erroneous.

Tips for Car Sensor Maintenance and Care

This being a maintenance founded article I feel the necessity to give you tips on how to be proactive in the maintenance and care of the four or five sensors on your vehicle.

1. If you sensors do not have valve covers on them get a set and put them on.
2. Before you decide to crank down on that valve stem, TPMS sensors need to be torqued to a specified limit with a special tool.
3. Try not to hit curbs or abutments damaging the tire or the wheel.
4. Do not ignore the proper inflation parameters of the vehicle. They are usually on the driver’s door pillar, and remember if you are underinflated or over inflated the light will still come on. If you change tire sizes or wheel sizes remember to have your on board computer re flashed to compensate, as this will not only affect the tire pressures, ABS operation and speedometer accuracy.
5. Sensors do not like heat, debris or water, all of which are inside of every tire, unless you run your tires with nitrogen as I do and often tell others to.

Tire Pressure Monitoring System

Tire Pressure Monitoring System

The bottom line is as such; TPMS systems provide a measure of safety when used as designed; they promote better tire wear and fuel economy as side effects which save you money. The down side is if you start to realize that there is a battery issue, it is most prudent to bite the bullet and replace all four, and that damn annoying orange light is always on.


Gregg’s Automotive Maintenance & Repair Center

236 S. Tamiami Tr.
Punta Gorda, Fl. 33950
Auto Repair, A/C Repair, Oil Change, Brake Repair & Transmission Services